This invention relates to apparatus for suppression and control of engine exhaust noise sound levels and engine performance. Such apparatus may be known as mufflers for use on automobiles and other types of vehicles and may have adjustable elements for suppression of various frequency noises during varying engine operating conditions. The new exhaust noise control apparatus has an adjustable control valve positionable in a multi-chamber muffler.
Mufflers, variable resonating chamber devices, and automobile exhaust noise suppressor apparatus may be known for use with internal combustion engines and other types of engines that produce a gas discharge and varying frequency noise sound. The mufflers for use in suppressing noise produced by the exhaust of an engine may have multiple chambers formed in the structure of the muffler by the use of baffles or interior walls that may have ports or openings therein and may have interior pipes or tubes for controlling the flow of the gas. The velocity, frequency and pressure of the exhaust gas may be used to change, suppress and resonate the noise frequency and level prior to the exhaust gas exiting the muffler.
In some types of mufflers with baffles and multiple chambers a baffle may have a port formed therein that has a valve to open and close the port based on the pressure of the gas impinging on the valve. This may change the flow of gas into different chambers that may be resonating chambers or allow the gas to exit the muffler from more than one exhaust pipe. Other types of mufflers with baffles may have a variable resonation chamber valve that is rotatable in and out of a valve seat in a chamber port by operation of a rotatable shaft that the chamber valve is attached to adjacent to an edge or wall portion of the valve that may have mounting arms. These types of valves require mechanisms external to the muffler to allow rotation of the shaft and retaining the shaft in position that may include an arm or extension member. This type of structure may also include use of an actuator device to allow rotation of the shaft. The drawback or problem with these various chamber valve devices is the complex structure subject to damage in land vehicle use or lack of access to the valve position control mechanism for adjustment.